Study of Re strengthening mechanisms in nickel-based superalloy

Re doping is an essential way to improve the high temperature mechanical properties of nickel -based single crystal superalloy (NBSCS). However, how the doped Re affects the mechanical properties of NBSCS is still unclear, and a quantitative description is lacking. This paper attempts to study the influence of Re doping on plastic deformation mechanisms of NBSCS at atomic scale. First, the grand -canonical Monte Carlo method was employed to determine the distribution of Re atoms within the two-phase microstructure of NBSCS. Then, the molecular dynamics simulations were carried out to study the effect of Re doping on the dislocation motion and evolution during plastic deformation, with a focus on two important deformation mechanisms in NBSCS, i.e., dislocation gliding in the hairpin -like shape in the narrow gamma matrix channel and dislocation cutting into the gamma ' precipitation from the gamma matrix. The results show that Re atoms prefer to segregate at the gamma/gamma ' interface. The increase of Re concentration in NBSCS can significantly improve both the critical stress of dislocations gliding in the gamma matrix channel and the critical stress of dislocation cutting into the gamma ' precipitation. These simulation results are qualitatively consistent with experimental observations. Based on these atomic scale simulations, two quantitative models for screw dislocation gliding in a hairpin -like shape in the gamma matrix channel and dislocation cutting into the gamma ' precipitation in the super -dislocation pair that take into account the Re doping effects have been proposed. The good agreement between the molecular dynamics simulation and the model prediction suggests that these quantitative models can be used for up -scale simulations of the dislocation movement and evolution in the presence of Re doping in NBSCS.